1. Field of the Invention
The present invention relates to an air-conditioning control apparatus provided on an automobile or the like, and more particularly to an air-conditioning control apparatus capable of setting a temperature to a level as desired by varying an opening and closing angle of an air-mix door.
2. Description of the Prior Art
FIG. 6 is a schematic view for explaining a general air-conditioner provided on an automobile.
As shown in FIG. 6, various doors of which functions are different from each other are provided within the air-conditioner. First, switching of internal and external air is carried out by an intake door 2 which selects whether in-vehicle air or out-vehicle air is used for air taken into the air-conditioner. The air having passed through the intake door 12 is fed to an evaporator 14 by means of a fan motor 13. The evaporator 14 has the function to forcibly cool the thus feed air to delivery the same. The air having passed through the evaporator 14 is divided into one which is used as cool air and the other which is heated by a heater core 15 for use as hot air. The cool air and hot are mixed later on to form air having a moderate temperature. The air mixing door 11 is provided in order to determine a ratio of mixture between the cool air and hot air. Accordingly, air having the desired temperature is obtained by the opening and closing state of the air mixing door 11. The thus obtained air is then fed to a venting door 17, a floor-door 18 and a def-door 19. Tbe respective blowing openings are selected according to the opening and closing state of these doors 17, 18 and 19, and the air having a moderate temperature is obtained through the selected blowing opening.
Various doors are provided on the air-conditioner for an automobile as described above. Among these doors, the intake door 12, venting door 17, floor-door 18 and def-door 19 will merely suffice to be either opened or closed but only the air-mixing door 11 is required for its various opening and closing states. Therefore, the door 11 is required to perform the continuous opening and closing operation.
FIG. 7 is a perspective view showing a prior art example of a driving device for the air-mixing door, in which figure, reference numeral 20 designates an L-shaped lever, and 21 designates a wire.
In FIG. 7, the lever 20 is pivotable in a direction as indicated by arrow A--A around a pivot 20b whilst the air-mixing door 11 is pivotable in a direction as indicated by arrow B--B around a pivot 11a, a wire 21 being extended between an end 20c of the lever 20 and the air-mixing door 11. Accordingly. wben an operating portion 20a provided on one end of the lever 20 is moved in a direction as indicated by arrow A--A by a finger, this movement is transmitted to the air-mixing door 11 through the wire 11 so that the air-mixing door 11 may be rotated through an angle as desired in correspondence to the amount of movement of the lever 20.
The operation of the conventional air-conditioning control apparatus provided with the lever 20 as described above is illustrated in FIGS. 8 through 10.
FIG. 8 shows the state wherein the door 11 is fully opened and the door 12 is opened toward the outside-air introducing side, FIG. 9 the state wherein the door 11 is fully opened and the door 12 is opened towards the outside introducing side, FIG. 10 the state wherein the door 11 is fully opened and the door 12 is opened toward tbe inside air introducing side, respectively.
Referring to FIGS. 8 through 10, the lever 20 is specifically composed of an operating lever 22, a traction lever 23 and a cam plate 24, the operating lever 22 being pivotable relative to a pivot 25, the traction lever 23 being pivotable relative to a pivot 26. The operating lever 22 is formed into an inverted L-shape on the wbole in plane. At the end of a portion on the long side of the lever 22 is provided a slidable slide 26 along a slide groove 25 formed in the air-conditioning apparatus body 1 and guide grooves 22a and 22b being bored therein, whereas at the end of a portion on the short side of the lever 22 is formed with a switcb operating portion 22c which depresses an operating switch 12a of the intake door 12. The traction lever 23 is also formed into an inverted L-shape in plane and has an engaging portion 23a with which the wire 21 is engaged, an insert hole 23b bored externa1ly of a shaft 26 on the opposite end, and a projection 23c projected in the middle portion. The cam plate 24 transmits the pivotal operation of the operating lever 22 to the traction lever 23, the cam plate 24 comprising a guide groove 24a having an L-shape on the whole inserted into the projection 23c, an insert hole 24b externally of the shaft 25, and a projection 24c inserted into the guide groove 22a. A wire spring 27 is provided between the upper surface of the operating lever 22 and the projection 23c of the traction lever 23 to always urge the traction lever 23 in a direction as indicated by arrow C in FIG. 8.
Next, the interrelationship between the aforementioned three elements and the operation thereof will be described hereinafter.
The traction lever 23 is pivotably mounted on the shaft 26 through the insert hole 23b formed to have a larger diameter tban that of tbe shaft 26, and the projection 23c is loosely fitted into the guide groove 24a of the cam plate 24. The insert hole 24b formed in the cam plate 24 is also formed to have a larger diameter than that of the shaft 25 and is loosely fitted rotatably into the shaft 25 in consideration of a clearance to some extent. The projection 24c is inserted into the guide groove 22a of the operating lever 22, and may be moved along the guide groove 22a. With the structure of three elements as described above, tbe operation of the operating lever 22 is transmitted to the cam plate 24 through the projection 24c, and the operation of the cam plate 24 is transmitted to the traction lever 23 through the guide groove 24a.
More specifically, in the state as shown in FIG. 8, the traction lever 23 pulls the wire 21 at its maximum, and therefore the air mixing door 11 is also opened to guide the introduced outside air as hot air toward the vehicle rooms through the heater core 15. When the operating knob 28 projected frontwardly of the air-conditioning control apparatus body 1 is moved in a direction as indicated by arrow D from the aforesaid state, the slide 26 linearly moves along the slide groove 25 and the operating lever 22 pivots in a direction as indicated by arrow E relative to the shaft 25. At that time, the end of the operating lever 22 linearly moves and the operating lever 22 body pivots, and therefore the radius of the pivotal movement varies according to the pivotal angle and the operating lever 22 is rotated while being moved in a direction as indicated by arror F along the guide groove 22b. During this pivotal movement, the cam plate 24 is pivotally moved in a direction as indicated by arrow E (clockwise in the figure) while the projection 24c is moving within the guide groove 22a.
When the cam plate 24 is pivotally moved in the direction of arrow E, the internal wall of the guide groove 24a pushes the projection 23c of the traction lever 23 to turn the traction lever 23 similarly in the direction of arrow E. Thus, the air-mixing door 11 is actuated in the closing direction by the wire 21. When the operating knob 28 is made to slide up to the position of FIG. 9, the air-mixing door 11 is completely closed. At this time, the projection 23c moves along the internal wall portion of the cam groove 24a till it reaches the neighborhood of the top 24d of the bended portion. When the knob is further slidably moved in the direction of arrow D from the position of FIG. 9, the traction lever 23 maintains its rotational angle, and the operating lever 22 and the cam plate 24 are further pivotally moved in the direction of arrow E. With this, the pressing portion 22c comes into contact with the operating switch 12a to force the end of the switch 12a into the apparatus body 1 to turn on the operating system of the intake door 12. When the operating system is turned on, the intake door 12 is switched from the outside air introducing side to the inside air introducing side to interrupt the introduction of the outside air.
In the above-described air-conditioning control apparatus, mostly the driver operates the operating knob 28 and often operates the knob during the travel. Therefore, a sort of a position recognition function is demanded so that the operator may definitely judge the heater mode from the position of FIG. 8 to the position of FIG. 9 (only during this mode, the air-mixing door 11 is open, and the outside air according to the opening degree thereof passes through the heater core 15 to render the heater effective) and the recirculation mode wherein air is circulated only within the vehicle compartments. In order to provide this function, the guide groove 24a is formed into an L shape, and the operating force increases at a position in which the projection 23c gets over the top 24c. That is, as shown in FIG. 11a, it relatively moves in the direction of arrow G from the position of the projection 23c corresponding to FIG. 8 to a position of FIG. 11b corresponding to FIG. 9. At that time, the projection 23c is positioned immediately before the top 24d to increase the operating force, thus finishing the heater mode.
Next, when further moving from the FIG. 9 position in tbe direction of arrow D, the cam plate 24 is also rotated in the direction of arrow E and the top 24c of the guide groove 24a comes into contact with the side of the projection 23c to press the latter. Then, the cam plate 24 is slightly moved in the direction of arrow C since the insert hole 24b is formed to have a larger diameter than that of the shaft 25. On the other hand. the traction lever 23 is slightly moved in the direction of arrow H since the insert hole 23b is formed to have a larger diameter than that of the shaft 26. and the projection 23c gets over the top 24d as shown in FlG. 11c and reaches the groove on the Q side. The traction lever 23 maintains the same position on the whole and assumes the state as shown in FIG. 10 and FIG. 11d to effect the aforementioned operation of the intake door 12.
In the aforementioned prior art, in order that the heater mode (the operating zone in connection with the air-mixing door 11) and the recirculation mode (the non-operating zone in connection with the air-mixing door 11) may be definitely discriminated from each other, the guide groove 24 is formed into an L shape on the whole, and the operating force increases in the vicinity of the top 24d of the guide groove 24a. When the great operating force is further applied, the cam plate 24 and the traction lever 23 are relatively deviated so as to get over the top 24d. This is the mechanism employed because the projection 23c is secured to the traction lever 23. In this mechanism, since the cam plate 24 and the traction lever 23 are relatively deviated a dimensional allowance is provided between the shafts 25 and 26 and between the insert holes 24b and 23b as mentioned above. This allowance is recognized as a play when the operating knob 28 is operated, which leads to a cause for injuring the operating feeling. Particularly, this play poses a problem when the operating knob 28 is operated from the fully open state to the closed state in FIG. 8
As may be understood from FIG. 6, in the fully open state, the air-mixing door 11 is urged toward the opening side by pressure of the outside air introduced from the outside, and therefore even if the operating knob 28 is operated toward the closing side, the traction lever 23 cannot be actuated unless the play resulting from the aforesaid dimensional allowance has been completely absorbed. Accordingly, the lever is lightly actuated up to the position in which the play is overcome, and from the position in which the play has been overcome, the operating force for opening the air-mixing door 11 against the air pressure increases, thus deteriorating the operatability. In addition, there arises the case where the sliding amount of the operating knob 28 and the opening degree of the air-mixing door 11 do not correspond to each other in the ratio of 1:1, thus posing a problem that the fine adjustment of temperature is difficult to make.